Polymers and copolymers of hydroxy acids, generally known as poly(hydroxy acid)s, slowly hydrolyze and biodegrade to environmentally benign products. These polymers are well behaved thermoplastics with appealing aesthetic qualities. Consequently, high molecular weight polymers (that is, those having a molecular weight of at least 10,000 and typically in the range of 15,000 to 500,000) of hydroxy acids, especially lactic acid and glycolic acid, are potential replacements for poly(styrene) and other non-biodegradable polymers in numerous applications, such as packaging. However, a major disadvantage of such polymers as a food packaging materials is that they have relatively high moisture permeability, which would decrease the self-life of foods packaged in such material. This invention is based on the discovery that adding a metalized layer to films of these poly(hydroxy acid)s dramatically improves their impermeability to moisture, without adversely interfering with their environmentally benign character. In addition, these metalized poly(hydroxy acid) films can be quite decorative, thus making such materials the ones of choice for use in packaging.